/**
 * 
 */
package org.swing.utility.jdbc.resultset;

import java.io.InputStream;
import java.io.Reader;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.math.BigDecimal;
import java.net.URL;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.Ref;
import java.sql.ResultSet;
import java.sql.Time;
import java.sql.Timestamp;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import org.swing.utility.jdbc.helper.ProxyFactory;

/**
 * @author lqnhu
 *
 */
public class SqlNullCheckedResultSet implements InvocationHandler {
	/**
	 * Maps normal method names (ie. "getBigDecimal") to the corresponding null
	 * Method object (ie. getNullBigDecimal).
	 */
	private static final Map<String, Method> nullMethods = new HashMap<String, Method>();
	static {
		Method[] methods = SqlNullCheckedResultSet.class.getMethods();
		for (int i = 0; i < methods.length; i++) {
			String methodName = methods[i].getName();
			if (methodName.startsWith("getNull")) {
				String normalName = "get" + methodName.substring(7);
				nullMethods.put(normalName, methods[i]);
			}
		}
	}
	/**
	 * The factory to create proxies with.
	 */
	private static final ProxyFactory factory = ProxyFactory.instance();

	/**
	 * Wraps the <code>ResultSet</code> in an instance of this class. This is
	 * equivalent to:
	 * 
	 * <pre>
	 * ProxyFactory.instance().createResultSet(new SqlNullCheckedResultSet(rs));
	 * </pre>
	 *
	 * @param rs
	 *            The <code>ResultSet</code> to wrap.
	 * @return wrapped ResultSet
	 */
	public static ResultSet wrap(ResultSet rs) {
		return factory.createResultSet(new SqlNullCheckedResultSet(rs));
	}

	private InputStream nullAsciiStream = null;
	private BigDecimal nullBigDecimal = null;
	private InputStream nullBinaryStream = null;
	private Blob nullBlob = null;
	private boolean nullBoolean = false;
	private byte nullByte = 0;
	private byte[] nullBytes = null;
	private Reader nullCharacterStream = null;
	private Clob nullClob = null;
	private Date nullDate = null;
	private double nullDouble = 0.0;
	private float nullFloat = 0.0f;
	private int nullInt = 0;
	private long nullLong = 0;
	private Object nullObject = null;
	private Ref nullRef = null;
	private short nullShort = 0;
	private String nullString = null;
	private Time nullTime = null;
	private Timestamp nullTimestamp = null;
	private URL nullURL = null;
	/**
	 * The wrapped result.
	 */
	private final ResultSet rs;

	/**
	 * Constructs a new instance of <code>SqlNullCheckedResultSet</code> to wrap
	 * the specified <code>ResultSet</code>.
	 * 
	 * @param rs
	 *            ResultSet to wrap
	 */
	public SqlNullCheckedResultSet(ResultSet rs) {
		super();
		this.rs = rs;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getAsciiStream</code> method.
	 *
	 * @return the value
	 */
	public InputStream getNullAsciiStream() {
		return this.nullAsciiStream;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getBigDecimal</code> method.
	 *
	 * @return the value
	 */
	public BigDecimal getNullBigDecimal() {
		return this.nullBigDecimal;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getBinaryStream</code> method.
	 *
	 * @return the value
	 */
	public InputStream getNullBinaryStream() {
		return this.nullBinaryStream;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getBlob</code> method.
	 *
	 * @return the value
	 */
	public Blob getNullBlob() {
		return this.nullBlob;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getBoolean</code> method.
	 *
	 * @return the value
	 */
	public boolean getNullBoolean() {
		return this.nullBoolean;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getByte</code> method.
	 *
	 * @return the value
	 */
	public byte getNullByte() {
		return this.nullByte;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getBytes</code> method.
	 *
	 * @return the value
	 */
	public byte[] getNullBytes() {
		if (this.nullBytes == null)
			return null;
		byte[] copy = new byte[this.nullBytes.length];
		System.arraycopy(this.nullBytes, 0, copy, 0, this.nullBytes.length);
		return copy;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getCharacterStream</code> method.
	 *
	 * @return the value
	 */
	public Reader getNullCharacterStream() {
		return this.nullCharacterStream;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getClob</code> method.
	 *
	 * @return the value
	 */
	public Clob getNullClob() {
		return this.nullClob;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getDate</code> method.
	 *
	 * @return the value
	 */
	public Date getNullDate() {
		return this.nullDate;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getDouble</code> method.
	 *
	 * @return the value
	 */
	public double getNullDouble() {
		return this.nullDouble;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getFloat</code> method.
	 *
	 * @return the value
	 */
	public float getNullFloat() {
		return this.nullFloat;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getInt</code> method.
	 *
	 * @return the value
	 */
	public int getNullInt() {
		return this.nullInt;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getLong</code> method.
	 *
	 * @return the value
	 */
	public long getNullLong() {
		return this.nullLong;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getObject</code> method.
	 *
	 * @return the value
	 */
	public Object getNullObject() {
		return this.nullObject;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getRef</code> method.
	 *
	 * @return the value
	 */
	public Ref getNullRef() {
		return this.nullRef;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getShort</code> method.
	 *
	 * @return the value
	 */
	public short getNullShort() {
		return this.nullShort;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getString</code> method.
	 *
	 * @return the value
	 */
	public String getNullString() {
		return this.nullString;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getTime</code> method.
	 *
	 * @return the value
	 */
	public Time getNullTime() {
		return this.nullTime;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getTimestamp</code> method.
	 *
	 * @return the value
	 */
	public Timestamp getNullTimestamp() {
		return this.nullTimestamp;
	}

	/**
	 * Returns the value when a SQL null is encountered as the result of
	 * invoking a <code>getURL</code> method.
	 *
	 * @return the value
	 */
	public URL getNullURL() {
		return this.nullURL;
	}

	/**
	 * Intercepts calls to <code>get*</code> methods and calls the appropriate
	 * <code>getNull*</code> method if the <code>ResultSet</code> returned
	 * <code>null</code>.
	 *
	 * @see java.lang.reflect.InvocationHandler#invoke(java.lang.Object,
	 *      java.lang.reflect.Method, java.lang.Object[])
	 * @param proxy
	 *            Not used; all method calls go to the internal result set
	 * @param method
	 *            The method to invoke on the result set
	 * @param args
	 *            The arguments to pass to the result set
	 * @return null checked result
	 * @throws Throwable
	 *             error
	 */
	public Object invoke(Object proxy, Method method, Object[] args)
			throws Throwable {
		Object result = method.invoke(this.rs, args);
		Method nullMethod = (Method) nullMethods.get(method.getName());
		// Check nullMethod != null first so that we don't call wasNull()
		// before a true getter method was invoked on the ResultSet.
		return (nullMethod != null && this.rs.wasNull()) ? nullMethod.invoke(
				this, (Object[]) null) : result;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getAsciiStream</code> method.
	 *
	 * @param nullAsciiStream
	 *            the value
	 */
	public void setNullAsciiStream(InputStream nullAsciiStream) {
		this.nullAsciiStream = nullAsciiStream;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getBigDecimal</code> method.
	 *
	 * @param nullBigDecimal
	 *            the value
	 */
	public void setNullBigDecimal(BigDecimal nullBigDecimal) {
		this.nullBigDecimal = nullBigDecimal;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getBinaryStream</code> method.
	 *
	 * @param nullBinaryStream
	 *            the value
	 */
	public void setNullBinaryStream(InputStream nullBinaryStream) {
		this.nullBinaryStream = nullBinaryStream;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getBlob</code> method.
	 *
	 * @param nullBlob
	 *            the value
	 */
	public void setNullBlob(Blob nullBlob) {
		this.nullBlob = nullBlob;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getBoolean</code> method.
	 *
	 * @param nullBoolean
	 *            the value
	 */
	public void setNullBoolean(boolean nullBoolean) {
		this.nullBoolean = nullBoolean;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getByte</code> method.
	 *
	 * @param nullByte
	 *            the value
	 */
	public void setNullByte(byte nullByte) {
		this.nullByte = nullByte;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getBytes</code> method.
	 *
	 * @param nullBytes
	 *            the value
	 */
	public void setNullBytes(byte[] nullBytes) {
		byte[] copy = new byte[nullBytes.length];
		System.arraycopy(nullBytes, 0, copy, 0, nullBytes.length);
		this.nullBytes = copy;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getCharacterStream</code> method.
	 *
	 * @param nullCharacterStream
	 *            the value
	 */
	public void setNullCharacterStream(Reader nullCharacterStream) {
		this.nullCharacterStream = nullCharacterStream;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getClob</code> method.
	 *
	 * @param nullClob
	 *            the value
	 */
	public void setNullClob(Clob nullClob) {
		this.nullClob = nullClob;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getDate</code> method.
	 *
	 * @param nullDate
	 *            the value
	 */
	public void setNullDate(Date nullDate) {
		this.nullDate = nullDate;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getDouble</code> method.
	 *
	 * @param nullDouble
	 *            the value
	 */
	public void setNullDouble(double nullDouble) {
		this.nullDouble = nullDouble;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getFloat</code> method.
	 *
	 * @param nullFloat
	 *            the value
	 */
	public void setNullFloat(float nullFloat) {
		this.nullFloat = nullFloat;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getInt</code> method.
	 *
	 * @param nullInt
	 *            the value
	 */
	public void setNullInt(int nullInt) {
		this.nullInt = nullInt;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getLong</code> method.
	 *
	 * @param nullLong
	 *            the value
	 */
	public void setNullLong(long nullLong) {
		this.nullLong = nullLong;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getObject</code> method.
	 *
	 * @param nullObject
	 *            the value
	 */
	public void setNullObject(Object nullObject) {
		this.nullObject = nullObject;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getRef</code> method.
	 *
	 * @param nullRef
	 *            the value
	 */
	public void setNullRef(Ref nullRef) {
		this.nullRef = nullRef;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getShort</code> method.
	 *
	 * @param nullShort
	 *            the value
	 */
	public void setNullShort(short nullShort) {
		this.nullShort = nullShort;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getString</code> method.
	 *
	 * @param nullString
	 *            the value
	 */
	public void setNullString(String nullString) {
		this.nullString = nullString;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getTime</code> method.
	 *
	 * @param nullTime
	 *            the value
	 */
	public void setNullTime(Time nullTime) {
		this.nullTime = nullTime;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getTimestamp</code> method.
	 *
	 * @param nullTimestamp
	 *            the value
	 */
	public void setNullTimestamp(Timestamp nullTimestamp) {
		this.nullTimestamp = nullTimestamp;
	}

	/**
	 * Sets the value to return when a SQL null is encountered as the result of
	 * invoking a <code>getURL</code> method.
	 *
	 * @param nullURL
	 *            the value
	 */
	public void setNullURL(URL nullURL) {
		this.nullURL = nullURL;
	}
}
